Only users who are listed in the Administrative Options in the Travel Tracker can change the setup tables.  Sign in as a system administrator to see who has access. You will see that the admin table also has a "Yes/No" option for you to give new admins access to the Configuration and/or Setup Tables tabs. 

Go to Configuration, Administrative options.
The emails listed in the Administrator User Names can edit the setup tables.

If you make changes, add admins, or change the Yes/No settings, be sure to click Save at the bottom of the screen.